Years after building a unique AI chatbot, Kim Sum uses the technology to create Somebody, a dating app built to connect — and linked to multiple crimes.

Seong Yun-o makes a pitch at work, then makes a new app connection. Sum reaches out to Yun-o after their unusual encounter. Murderous activity escalates.

After days of radio silence, Sum finally hears back from Yun-o. When Sum tries to meet another app connection, things quickly turn violent.

Sum and Yun-o take their relationship to the next level. Meanwhile, Gi-eun goes to the CEO of Spectrum to ask for access to her personal chat history.

Gi-eun confronts her catfish on Somebody, and soon finds herself in danger again. Mok-won performs a ceremony to ward off evil spirits for Sum.

Mok-won and Gi-eun need to blow off some steam, so they take Sum along to a night club. Later, Mok-won tries to get Sum to face the truth about Yun-o.

With the walls closing in and threats escalating, Yun-o begins receiving deeply disturbing video chat requests on Somebody.